github.com/m4gshm/gollections@v0.0.10/notsafe/notsafe.go (about)

     1  // Package notsafe provides unsafe helper functions
     2  package notsafe
     3  
     4  import (
     5  	"reflect"
     6  	"unsafe"
     7  )
     8  
     9  // GetTypeSize retrieves size of a type T
    10  func GetTypeSize[T any]() uintptr {
    11  	var t T
    12  	return unsafe.Sizeof(t)
    13  }
    14  
    15  // GetArrayPointer retrieves the pointer of a slice underlying array
    16  func GetArrayPointer[T any](elements []T) unsafe.Pointer {
    17  	return unsafe.Pointer(GetSliceHeader(elements).Data)
    18  }
    19  
    20  // GetArrayElem returns an element by index from the array referenced by an unsafe pointer
    21  func GetArrayElem[T any](array unsafe.Pointer, index int, elemSize uintptr) T {
    22  	return *(*T)(GetArrayElemRef(array, index, elemSize))
    23  }
    24  
    25  // GetArrayElemRef returns an element's pointer by index from the array referenced by an unsafe pointer
    26  func GetArrayElemRef(array unsafe.Pointer, index int, elemSize uintptr) unsafe.Pointer {
    27  	return unsafe.Pointer(uintptr(array) + uintptr(index)*elemSize)
    28  }
    29  
    30  // GetLen returns the length of elements
    31  func GetLen[T any](elements []T) int {
    32  	return GetSliceHeader(elements).Len
    33  }
    34  
    35  // GetSliceHeader retrieves the SliceHeader of elements
    36  func GetSliceHeader[T any](elements []T) *reflect.SliceHeader {
    37  	return GetSliceHeaderByRef(unsafe.Pointer(&elements))
    38  }
    39  
    40  // GetSliceHeaderByRef retrieves the SliceHeader of elements by an unsafe pointer
    41  func GetSliceHeaderByRef(elements unsafe.Pointer) *reflect.SliceHeader {
    42  	return (*reflect.SliceHeader)(elements)
    43  }
    44  
    45  // Noescape prevent escaping of t
    46  //
    47  //go:nosplit
    48  //go:nocheckptr
    49  func Noescape[T any](t *T) *T {
    50  	x := uintptr(unsafe.Pointer(t))
    51  	return (*T)(unsafe.Pointer(x ^ 0)) //nolint
    52  }
    53  
    54  // InHeap is generic link to runtime.inheap
    55  func InHeap[T any](t *T) bool {
    56  	return inheap(uintptr(unsafe.Pointer(t)))
    57  }
    58  
    59  //go:linkname inheap runtime.inheap
    60  func inheap(p uintptr) bool